Diffuser plate

ABSTRACT

There is disclosed herein a diffuser plate for separating coils of sheet metal stacked on a vertical axis in an annealing furnace, the plate comprising two superimposed layers of flat bars, the bars in one layer being straight with tapered edges and uniformly skewed with respect to true radii of the plate and the bars in the other layer being tapered and curved in a circumferential direction opposite to the slant of the bars in the first layer and overlapping said bars in said first layer.

United States Patent Inventor Robert Lee Corbett, Jr.

22732 Westlake Road, Rocky River, Ohio 44116 Appl. No. 46,407 Filed June 15, 1970 Patented Nov. 9, 1971 DIFFUSER PLATE 7 Claims, 7 Drawing Figs.

U.S. Cl 226/5 R, 263/47 A Int. Cl C2ld 1/00 Field of Search 263/47 R,

47 A; 266/5 R, 1 RY [56] References Cited UNITED STATES PATENTS 2,981,529 4/1962 Menough 263/47 A 3,145,982 8/1964 Ludwig 263/74 A 3,423,079 1/1969 McKeown 263/47 A Primary Examiner-Gerald A. Dost Anorney-J. H. Slough ABSTRACT: There is disclosed herein a diffuser plate for separating coils of sheet metal stacked on a vertical axis in an annealing furnace, the plate comprising two superimposed layers of flat bars, the bars in one layer being straight with tapered edges and uniformly skewed with respect to true radii of the plate and the bars in the other layer being tapered and curved in a circumferential direction opposite to the slant of the bars in the first layer and overlapping said bars in said first layer.

DIFFUSER PLATE This invention relates to the annealing of coils of metal in strip form and more particularly to an improved plate for separating adjacent coils in a stack and controlling the flow of heated gas between said coils.

In known forms of the type of furnace herein referred to, the coils of strip material are stacked coaxially upon a suitable base structure having a recirculating fan or blower dispoud therein. Each coil defines a central, coaxial opening or eye, and the fan is adapted to circulate a heated, protective atmosphere gas upwardly around the outside of the coils and downwardly through to the eyes of said coils. Plate members, sometimes referred to as coil separators or convector plates, are provided between adjacent pairs of the stacked coils to space the coils from each other and afford suitable gas passages whereby the heated gas circulates to the edges of the wraps and heat is transferred by convection and conduction to the interior of the coils. The stacked coils are preferably enclosed with a gastight inner cover which is, in turn, disposed within a suitable heating means for heating the inner cover. Details of a fumace of the type herein referred to are fully disclosed in applicant's copending'application, Ser. No. 731,529, filed May 23, 1968, and entitled Heat Transfer Plates.

The separating plate member of this invention, herein referred to as a diffuser plate, can be used as a coil separator, convector plate, or heat transfer plate and may further be used as a charge plate for supporting the entire stack of coils when the same is disposed upon the base of the furnace. It may further be used as a top orifice plate for positioning on top of the uppermost coil to restrict the flow of atmosphere gas into the eye of said uppermost coil. The diffuser plate of the present invention is adapted to transfer heat either from the circulating atmosphere gas to the coils or from the coils to a cooling atmosphere gas in an improved manner by both conduction and convection. It is designed to provide a controlled turbulence of the atmosphere gas adjacent to the edges of the coil wraps to more rapidly heat or cool the coils resulting in an increase of the overall efficiency of the furnace. The diffuser plate of the present invention is adapted to withstand the extreme stresses due to the weight ofthe coils and the extreme temperature changes within the furnace.

The diffuser plate of this invention comprises, in general, two layers of bars which overlap each other and are so arranged that each bar in each layer overlaps and is welded or otherwise suitably secured to a plurality of bars in the other layers. In one layer, the bars are very generally wedge shaped and arranged with their widest ends disposed outwardly to form the outer periphery of the plate and their inner ends disposed generally inwardly to define an inner, central opening of the plate. The generally wedge-shaped bars are uniformly skewed with respect-to true radii of the plate in one circumferential direction. The bars in the other layer also have wider outer than inner end portions and are curved in a direction opposite to the skewing of the bars in the first layer whereby each bar of a second layer overlaps and is welded to more than one bar of the first layer. Thus, the bars in both layers provide inwardly tapering gas passages which overlap passages provided by the bars of the other layer, the bars in the first layer affording straight gas passages and the bars of the second layer affording curved gas passages.

It is an object of this invention to provide a diffuser plate affording an improved flowof atmosphere gas to the edges of the coil wraps and into the eyes of the coils.

Another object of the invention is to provide a diffuser plate which creates a greater turbulence in the flowing gas than similar plates of known design.

A still further object of the invention is to provide a diffuser plate as set forth above which aflords a greater surface supporting area for the stacked coils.

Still another object of the invention is to provide a diffuser plate which is so constructed as to resist distortion due to expansion and contraction of the metal when subjected to extreme temperature changes.

Still another object of the invention is to provide a diffuser plate having the above features and characteristics wherein the supporting surface areas are proportioned according to the load weight of the coil diameters and are sufficient to support the coils without damage to the edges of the coil wraps while also affording adequate circulation of the atmosphere gas across edges of the coil wraps.

A still further object of the invention is to provide a diffuser plate of sufficiently sturdy construction whereby it can also be used as a'load or charge plate directly on top of the furnace base thereby causing additional atmosphere gas to come into contact with the bottom edge of the bottom coil directly from the recirculating fan.

Yet another object of the invention is to provide a diffuser plate which affords increased circulation downwardly through the eyes of the coils and upwardly around the outside of the coils.

Another object of the invention is to provide a diffuser plate of the above type which is of simple, sturdy, construction, is inexpensive to manufacture, and highly durable in use.

Other objects of the invention and the invention itself will be readily apparent from the following description of the invention and the accompanying drawings, in which said drawings:

FIG. 1 is a perspective view of the diffuser plate of this invention as seen generally from the top and outer edge thereof;

FIG. 2 is a bottom plan view of the diffuser plate of this invention;

FIG. 3 is a fragmentary top plan view showing only a portion of the diffuser plate;

FIG. 4 is an elevation looking directly at the edge of the diffuser plate from the front of the plate as viewed in FIG. 1;

FIG. 5 is a fragmentary, enlarged section taken along the curved line 5-5 of FIG. 3;

FIG. 6 is an enlarged fragmentary section taken along the curved line 6-6 of FIG. 3; and

FIG. 7 is a straight line section taken along the line 7-7 of FIG. 3.

Referring now to the drawings in all of which like parts are designated by like reference numerals, the difluser plate of this invention is generally indicated at 10. As particularly shown in FIG. 4, the diffuser plate 10 comprises two layers of generally circumferentially arranged bars, an upper layer generally indicated at A and a bottom layer generally indicated at B. The upper layer A comprises a plurality of generally wedge-shaped bars 12 having substantially wider outer end portions 13 and relatively narrower inner end portions 14. Each said bar 12 has inwardly converging, substantially straight side edges 16 and i7 and is skewed with respect to a true radius ofthe diffuser plate; that is, its outer end is circumferentially displaced relative to its inner end in a clockwise direction.

As best seen in FIG. 2, the layer B comprises a plurality of semicrescent-shaped bars 22 having relatively wider, outer end portions 23 and relatively narrower inner end portions 24. Each bar 22 is curved in a direction opposite to the slant or skewing of the bars 12 and has a convex side edge 26 and a concave side edge 27. Each bar 22 has its outer end portion 23 overlapping an outer end portion 13 of a bar 12, crosses over and is secured to an intermediate portion of an adjacent second bar 12, and has its inner end portion 24 overlapping an inner end portion 14 of a third bar 12. As shown in FIG. 2, the outer end portion 23 is ofiset inwardly a slight amount relative to the outer end portion 13 of the bar 12 to afford space for a weld 30 which extends across the outer ends of the bars and part way around the convex side edge 26. Said convex edge 26 of each bar 22 overlaps a bar 12 a substantial distance and is welded thereby to a second weld 31 which is discontinuous with the weld 30. Edge portions of the convex and concave side edges 26 and 27 which crossover the second or next adjacent bar 12 are secured to said bar 12 by welds 32 and 33. The innermost end portion 24 of each bar 22 is further provided with a short weld 34 along that portion of the concave side edge 27 which crosses a third bar 12.

By referring to FIG. 3, it will be seen that similar welding is provided on the top surface to secure the bars 12 of the upper layer A to the bars 22 of the bottom layer B. Where the side edge 16 of each bar 12 crosses a first bar 22, discontinuous weld portions 35 and 36 are provided which leave a substantially large, unwelded portion therebetween. Where a medial portion of each bar 12 crosses over a bar 22, overlapping portions of the side edges 16 and 17 are welded as indicated at 37 and 38, respectively. The innermost end portion of each bar 12 which is set outwardly a slight distance from the innermost edge of the bars 22 which it overlaps is provided with a weld 39 which extends around the side edge 17 at the portion thereof which overlaps one of the bars 22. Thus the two layers A and B are rigidly secured together with their longest overlapping portions being connected along the straight side edges 16 of the bars 12 and the convex side edges 26 of the bars 22 by a stitch or discontinuous weld to afford means for relative expansion and contraction of the bars in the two layers. It will be noted that each overlapping portion of each side edge 16 and 26 extends substantially more than one-half of the entire length of the edge of which it is a part.

The diffuser plate of this invention provides two different gas passages in two layers of bars which said passages intersect to allow the gas flowing in each set of passages to mix with gas flowing in the other set of passages. The straight side edges 16 and 17 of adjacent bars 12 provide generally straight, inwardly tapering and skewed passages whereas the convex and concave side edges 27 and 26, respectively, of adjacent bars 22 provide inwardly directed and substantially curved tapering passages which cross over the straight passages. Because of the curvature of the bars 22, the outer edge of the diffuser plate 10 is provided with a plurality of substantially open passages 40 which extend through both layers in the direction of the thickness of the plate and extend radially a substantial distance into the plate. At this point, the passage 40 branches off into a curved passage 41 and a straight passage 42 which extend into the central opening but which intersect again with a passage of the opposite layer adjacent to said opening as indicated at 43. Thus the gas drawn inwardly toward the central opening 15 initially moves freely into the passage 40 and is then abruptly divided into two passages 41 and 42 which eventually cross each other again and intersect at 43 before exhausting into the central opening 15. At each point where a passage is divided or caused to intersect, great turbulence is set up in the atmosphere gas which provides improved heating or cooling of the coils as'the gasses circulate around and across the end edges of the coil wraps.

The curvature of the bars are preferably in the direction of the fan rotation or in the direction of the arrows as shown in FIGS. 1 and 2. The straight bars are angled in a direction different to and generally opposing the direction of rotation of the fan in such manner as to offset any tendency of the atmosphere gas to set up a uniform swirling motion within the center of the diffuser plate or within the eyes of the coils. The central opening 15 of the diffuser plate is substantially smaller than the eyes of the coils placed thereon in such manner as to prevent the coil wraps from being drawn downwardly through a diffuser plate.

The present design provides a greater surface support for the coils while providing supporting surface areas which are invention as herein described and illustrated may be made without, however, departing from the spirit thereof or the scope of the appended claims.

What I claim is:

l. A diffuser plate for spacing coils of strip metal stacked coaxially within an annealing furnace, said diffuser plate comprising two eonti ous layers of flat metal bars disposed about a vertical was an circumferentially spaced from each other in each layer; the inner ends of said bars defining a substantially circular central opening about said axis whereby said bars form a flat, annular structure; the bars in one of said layers being substantially straight and skewed with respect to true radii of the plate in one circumferential direction and the bars in the other of said layers being curved in the opposite circumferential direction; each said bar in each said layer having an outer end portion overlapping the outer end portion of a first bar in said other layer, a medial portion overlapping a medial portion of a second bar in said other layer, and an inner end portion overlapping the inner end portion of a third bar of said other layer; adjacent bars in each said layer defining passages therebetween, each of said passages crossing over and open to passages of the other said layer.

2. A difi'user plate as set forth in claim 1: said bars and passages in both said layers tapering inwardly from the outer edge of said plate to said central opening.

3. A diffuser plate as set forth in claim 1: said substantially straight bars having substantially straight, inwardly converging side edges and said curved bars being semicrescent in shape and each having a convex and a concave side edge.

4. A diffuser plate as set forth in claim 1: each said bar in each said layer having the outer end portion thereof welded to the outer end portion of said first bar in said other layer, the medial portion thereof welded to a medial portion of said second bar in said other layer, and the inner end portion thereof welded to the inner end portion of said third bar of said other layer.

5. A diffuser plate as set forth in claim I: the bars in one of said layers being radially outwardly offset with respect to the bars in the other said layer, each bar in said one layer being welded across its inner end edge to the outer end portion of a bar in said other layer and each bar in said other layer being welded across its outer end edge to the outer end portion of a bar in said one layer.

6. A diffuser plate as set forth in claim 1: each said bar in each said layer having a substantial portion of one of its side edges overlapping a bar of the other said layer and welded thereto only at spaced areas to allow separate expansion and contraction of the bars due to temperature changes.

7. A diffuser plate as set forth in claim 1: each said bar in each said layer having more than one-half of one of its side edges overlapping a bar of the other said layer and welded thereto only at spaced areas to allow separate expansion and contraction of the bars due to temperature changes.

i t t 0 t 

1. A diffuser plate for spacing coils of strip metal stacked coaxially within an annealing furnace, said diffuser plate comprising two contiguous layers of flat metal bars disposed about a vertical axis and circumferentially spaced from each other in each layer; the inner ends of said bars defining a substantially circular central opening about said axis whereby said bars form a flat, annular structure; the bars in one of said layers being substantially straight and skewed with respect to true radii of the plate in one circumferential direction and the bars in the other of said layers being curved in the opposite circumferential direction; each said bar in each said layer having an outer end portion overlapping the outer end portion of a first bar in said other layer, a medial portion overlapping a medial portion of a second bar in said other layer, and an inner end portion overlapping the inner end portion of a third bar of said other layer; adjacent bars in each said layer defining passages therebetween, each of said passages crossing over and open to passages of the other said layer.
 2. A diffuser plate as set forth in claim 1: said bars and passages in both said layers tapering inwardly from the outer edge of said plate to said central opening.
 3. A diffuser plate as set forth in claim 1: said substantially straight bars having substantially straight, inwardly converging side edges and said curved bars being semicrescent in shape and each having a convex and a concave side edge.
 4. A diffuser plate as set forth in claim 1: each said bar in each said layer having the outer end portion thereof welded to the outer end portion of said first bar in said other layer, the medial portion thereof welded to a medial portion of said second bar in said other layer, and the inner end portion thereof welded to the inner end portion of said third bar of said other layer.
 5. A diffuser plate as set forth in claim 1: the bars in one of said layers being radially outwardly offset with respect to the bars in the other said layer, each bar in said one layer being welded across its inner end edge to the outer end portion of a bar in said other layer and each bar in said other layer being welded across its outer end edge to the outer end portion of a bar in said one layer.
 6. A diffuser plate as set forth in claim 1: each said bar in each said layer having a substantial portion of one of its side edges overlapping a bar of The other said layer and welded thereto only at spaced areas to allow separate expansion and contraction of the bars due to temperature changes.
 7. A diffuser plate as set forth in claim 1: each said bar in each said layer having more than one-half of one of its side edges overlapping a bar of the other said layer and welded thereto only at spaced areas to allow separate expansion and contraction of the bars due to temperature changes. 